1. Field of the Invention
The invention relates to a vehicle control device and a vehicle control method.
2. Description of Related Art
In recent vehicles, a control device that automatically executes control during running of the vehicle has been developed in order to improve ease of driving during running of the vehicle, reduce a burden on driver's driving operation and further improve safety during running of the vehicle.
For example, in a vehicle rear-end collision prevention system described in Japanese Patent Application Publication No. 9-27100 (JP-A-9-27100), a vehicle that runs ahead (preceding vehicle) is extracted from a captured image ahead of a host vehicle and, when there is a possibility that the host vehicle hits the rear end of the preceding vehicle, automatic braking is performed. In addition, when it is determined whether there is a possibility that the host vehicle hits the rear end of a preceding vehicle, the size of the vehicle extracted from the captured image is determined, and, for example, when the preceding vehicle is a small-sized vehicle, deceleration timing is advanced or the braking force of a braking mechanism is increased in preparation for sudden braking of the preceding vehicle having high braking performance. By so doing, it is possible to appropriately prevent the host vehicle from hitting the rear end of the preceding vehicle.
Here, in recent years, there has been developed follow-up running control that causes a host vehicle to follow a preceding vehicle to reduce a burden on a driver. In the follow-up running control, the host vehicle is accelerated or decelerated so as to keep an inter-vehicle time between the preceding vehicle and the host vehicle (that is, a time that elapses until the front end of the host vehicle reaches the same position as the current position of the rear end of the preceding vehicle) at a predetermined period of time. However, the braking response characteristic at the time of braking may significantly vary depending on the type of a vehicle, and, when a variation in the deceleration of a preceding vehicle is larger than a variation in the deceleration of the host vehicle, it is difficult to keep the inter-vehicle time between the preceding vehicle and the host vehicle during deceleration of the preceding vehicle. In this case, there has been a case where it is difficult to continue follow-up running.